Retirement Plans, Components of Net Periodic Benefit Cost for the Pension and Postretirement Tables (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
RAP
Net period benefit cost for the pension and postretirement plans
Service cost	$ 923	$ 2,075
Interest cost	1,772	1,623
Expected return on plan assets	(6,736)	(6,430)
Amortization of prior service cost	(63)	(18)
Amortization of actuarial loss	74	1,050
Total net periodic pension cost	(4,029)	(1,701)
Postretirement Plan
Net period benefit cost for the pension and postretirement plans
Interest cost	13	13
Amortization of prior service cost	(19)	(19)
Total net periodic pension cost	$ (6)	$ (6)